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Diffstat (limited to 'qemu/roms/u-boot/doc/README.arm-relocation')
| -rw-r--r-- | qemu/roms/u-boot/doc/README.arm-relocation | 193 |
1 files changed, 0 insertions, 193 deletions
diff --git a/qemu/roms/u-boot/doc/README.arm-relocation b/qemu/roms/u-boot/doc/README.arm-relocation deleted file mode 100644 index 645b3746c..000000000 --- a/qemu/roms/u-boot/doc/README.arm-relocation +++ /dev/null @@ -1,193 +0,0 @@ -To make relocation on arm working, the following changes are done: - -At arch level: add linker flag -pie - - This causes the linker to generate fixup tables .rel.dyn and .dynsym, - which must be applied to the relocated image before transferring - control to it. - - These fixups are described in the ARM ELF documentation as type 23 - (program-base-relative) and 2 (symbol-relative) - -At cpu level: modify linker file and add a relocation and fixup loop - - the linker file must be modified to include the .rel.dyn and .dynsym - tables in the binary image, and to provide symbols for the relocation - code to access these tables - - The relocation and fixup loop must be executed after executing - board_init_f at initial location and before executing board_init_r - at final location. - -At board level: - - dram_init(): bd pointer is now at this point not accessible, so only - detect the real dramsize, and store it in gd->ram_size. Bst detected - with get_ram_size(). - -TODO: move also dram initialization there on boards where it is possible. - - Setup of the the bd_t dram bank info is done in the new function - dram_init_banksize() called after bd is accessible. - -At lib level: - - Board.c code is adapted from ppc code - -* WARNING ** WARNING ** WARNING ** WARNING ** WARNING ** WARNING ** WARNING * - -Boards which are not fixed to support relocation will be REMOVED! - ------------------------------------------------------------------------------ - -For boards which boot from spl, it is possible to save one copy -if CONFIG_SYS_TEXT_BASE == relocation address! This prevents that uboot code -is copied again in relocate_code(). - -example for the tx25 board booting from NAND Flash: - -a) cpu starts -b) it copies the first page in nand to internal ram - (spl code) -c) end executes this code -d) this initialize CPU, RAM, ... and copy itself to RAM - (this bin must fit in one page, so board_init_f() - don;t fit in it ... ) -e) there it copy u-boot to CONFIG_SYS_NAND_U_BOOT_DST and - starts this image @ CONFIG_SYS_NAND_U_BOOT_START -f) u-boot code steps through board_init_f() and calculates - the relocation address and copy itself to it - -If CONFIG_SYS_TEXT_BASE == relocation address, the copying of u-boot -in f) could be saved. - ------------------------------------------------------------------------------ - -TODO - -- fill in bd_t infos (check) -- adapt all boards - -- maybe adapt CONFIG_SYS_TEXT_BASE (this must be checked from board maintainers) - This *must* be done for boards, which boot from NOR flash - - on other boards if CONFIG_SYS_TEXT_BASE = relocation baseaddr, this saves - one copying from u-boot code. - -- new function dram_init_banksize() is actual board specific. Maybe - we make a weak default function in arch/arm/lib/board.c ? - ------------------------------------------------------------------------------ - -Relocation with SPL (example for the tx25 booting from NAND Flash): - -- cpu copies the first page from NAND to 0xbb000000 (IMX_NFC_BASE) - and start with code execution on this address. - -- The First page contains u-boot code from drivers/mtd/nand/mxc_nand_spl.c - which inits the dram, cpu registers, reloacte itself to CONFIG_SPL_TEXT_BASE and loads - the "real" u-boot to CONFIG_SYS_NAND_U_BOOT_DST and starts execution - @CONFIG_SYS_NAND_U_BOOT_START - -- This u-boot does no RAM init, nor CPU register setup. Just look - where it has to copy and relocate itself to this address. If - relocate address = CONFIG_SYS_TEXT_BASE (not the same, as the - CONFIG_SPL_TEXT_BASE from the spl code), then there is no need - to copy, just go on with bss clear and jump to board_init_r. - ------------------------------------------------------------------------------ - -How ELF relocations 23 and 2 work. - -TBC - -------------------------------------------------------------------------------------- - -Debugging u-boot in RAM: -(example on the qong board) - ------------------ - -a) start debugger - -arm-linux-gdb u-boot - -[hs@pollux u-boot]$ arm-linux-gdb u-boot -GNU gdb Red Hat Linux (6.7-2rh) -Copyright (C) 2007 Free Software Foundation, Inc. -License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> -This is free software: you are free to change and redistribute it. -There is NO WARRANTY, to the extent permitted by law. Type "show copying" -and "show warranty" for details. -This GDB was configured as "--host=i686-pc-linux-gnu --target=arm-linux". -The target architecture is set automatically (currently arm) -.. -(gdb) - ------------------ - -b) connect to target - -target remote bdi10:2001 - -(gdb) target remote bdi10:2001 -Remote debugging using bdi10:2001 -0x8ff17f10 in ?? () -(gdb) - ------------------ - -c) discard symbol-file - -(gdb) symbol-file -Discard symbol table from `/home/hs/celf/u-boot/u-boot'? (y or n) y -No symbol file now. -(gdb) - ------------------ - -d) load new symbol table: - -(gdb) add-symbol-file u-boot 0x8ff08000 -add symbol table from file "u-boot" at - .text_addr = 0x8ff08000 -(y or n) y -Reading symbols from /home/hs/celf/u-boot/u-boot...done. -(gdb) c -Continuing. -^C -Program received signal SIGSTOP, Stopped (signal). -0x8ff17f18 in serial_getc () at serial_mxc.c:192 -192 while (__REG(UART_PHYS + UTS) & UTS_RXEMPTY); -(gdb) - -add-symbol-file u-boot 0x8ff08000 - ^^^^^^^^^^ - get this address from u-boot bdinfo command - or get it from gd->relocaddr in gdb - - => bdinfo -rch_number = XXXXXXXXXX -boot_params = XXXXXXXXXX -DRAM bank = XXXXXXXXXX --> start = XXXXXXXXXX --> size = XXXXXXXXXX -ethaddr = XXXXXXXXXX -ip_addr = XXXXXXXXXX -baudrate = XXXXXXXXXX -TLB addr = XXXXXXXXXX -relocaddr = 0x8ff08000 - ^^^^^^^^^^ -reloc off = XXXXXXXXXX -irq_sp = XXXXXXXXXX -sp start = XXXXXXXXXX -FB base = XXXXXXXXXX - -or interrupt execution by any means and re-load the symbols at the location -specified by gd->relocaddr -- this is only valid after board_init_f. - -(gdb) set $s = gd->relocaddr -(gdb) symbol-file -(gdb) add-symbol-file u-boot $s - -Now you can use gdb as usual :-) |